The team behind the open source ConfirmedVPN that launched last December is out today with another security-focused app for iOS called Lockdown. The new free app is what the developer says is the first open source firewall and works completely on device to block apps from crypto mining, sharing data with Facebook, and can block custom domains as well.

Lockdown was developed by Duet Display CEO Rahul Dewan and former iCloud engineer Johnny Lin. The open source firewall allows users to block connections to any website between its default setting and custom options.